There's only two options (and whether you are a citizen or resident makes no difference):
- If the parents have significant money to invest (think seven figures here), there's the Parent Retirement Resident Visa.
- Otherwise, there's the Parent Resident Visa, where your partner is required to sponsor her parents, and will require a substantial annual salary to do so -- to sponsor 2 parents, either your partner must earn 3 times the NZ median income ($159,120), or you and your partner combined must earn 4 times the NZ median income ($212,160).
If they are 56 or older, there is no other residence pathway for them.